Is their any way to change a car's interior to something way more fancier?

There are Custom Auto Interior Specialist that can upgrade your vehicle interior but switching one interior from a different make vehicle does not work well.

a) It's "is THERE...?", not "is THEIR...? Fail

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b) The answer is yes. That's one of the things automotive upholstery shops do. 

I mean Bentley interiors are okay but most 2020 cars already have nice interiors. If I could swap out my current hyundai accent interior for a bentley interior at a cost of 1000 dollars I might do it, but anything over 2k, not worth it to me. My interior is good enough.

It's usually simply not worth the time and money to do stuff like that - by the time you shell out the money to have it done, you might as well just upgrade to a car with a fancier interior.

Yeah - budget about $10,000 for the pink fuzzy velour & fake fur . . . . . about $20,000 for leather . . . . about $50,000 for a Bentley-level job.  It takes a bespoke shop to do work like that - everything custom, not "off the shelf" . . . . and make sure they use appropriate materials for a car:  suitable for great temperature variances,  won't fade in sunlight,  meets government standards for flamability, wood and other trim is shatter-proof,  doesn't interfere with functions of air bags, HVAC, etc.  

Or you could just buy a better car.